Numerous wheel assemblies have been devised employing various types of anti-friction rolling elements, including planetary systems, for permitting the wheel to be rotatably supported on or relative to an axle. While such wheel assemblies have normally performed in a manner which has been considered satisfactory, nevertheless there has been a long term and continuous effort to improve on such wheel assemblies so as to make them more free-wheeling, as by minimizing the internal friction of the wheel assembly, while at the same time maintaining or improving the durability of the wheel assembly. This problem of providing a wheel assembly which is substantially free-wheeling, that is possesses minimum friction, and at the same time possesses desirable wear and durability characteristics, has been further compounded by the additional difficulties created due to use of many wheels under contaminating environmental conditions (such as snow, water, liquids, dust and the like) which tend to contaminate the bearings, thereby greatly increasing both wear and rolling friction.
Thus, it is an object of the present invention to overcome many of the disadvantages associated with known wheel assemblies by providing an improved wheel assembly which results in a significant improvement in the rotational characteristics thereof by minimizing the rolling friction within the wheel assembly, while at the same time resulting in a wheel assembly having desirable durability. These desirable objectives are achieved in the improved wheel assembly of this invention by providing a wheel assembly having an increased number of rotational freedoms between the various parts of the wheel assembly, whereby the wheel more closely approaches a freely rotating system, thereby greatly minimizing the driving energy required to effect such rotation.
In the improved wheel assembly of this invention, the wheel includes an annular rim having the outer bearing race formed directly on the inner periphery thereof. A minimal number of substantially cylindrical rollers are positioned within the rim so as to be in rolling engagement with the aforesaid outer bearing race, which rollers in turn are normally rollingly engaged with an inner bearing race formed directly on the center support axle. The cylindrical rollers are themselves individually rotatably supported on suitable axles, which axles in turn are rotatably supported on and extend between a pair of retainer rings. The retainer rings themselves are freely rotatable relative to both the rim and the support shaft. Suitable end caps are fixed to the rim and closely confine the retainers and cylindrical rollers so as to sealingly enclose same. In a preferred embodiment, the end caps also retain the cylindrical rollers and retainers in an assembled condition with the rim irrespective of the presence of the support shaft.
Other objects and purposes of the invention will be apparent to persons familiar with wheel assemblies upon reading the following specification and inspecting the accompanying drawings.